Re: [PATCH RFC 50/77] mlx5: Update MSI/MSI-X interrupts enablement code

Alexander Gordeev
2013-10-03T19:48:39Z

On Thu, Oct 03, 2013 at 10:14:33AM +0300, Eli Cohen wrote:
> On Wed, Oct 02, 2013 at 12:49:06PM +0200, Alexander Gordeev wrote:
> >
> > + err = pci_msix_table_size(dev->pdev);
> > + if (err < 0)
> > + return err;
> > +
> > nvec = dev->caps.num_ports * num_online_cpus() + MLX5_EQ_VEC_COMP_BASE;
> > nvec = min_t(int, nvec, num_eqs);
> > + nvec = min_t(int, nvec, err);
> > if (nvec <= MLX5_EQ_VEC_COMP_BASE)
> > return -ENOSPC;
>
> Making sure we don't request more vectors then the device's is capable
> of -- looks good.
> >
> > @@ -131,20 +136,15 @@ static int mlx5_enable_msix(struct mlx5_core_dev *dev)
> > for (i = 0; i < nvec; i++)
> > table->msix_arr[i].entry = i;
> >
> > -retry:
> > - table->num_comp_vectors = nvec - MLX5_EQ_VEC_COMP_BASE;
> > err = pci_enable_msix(dev->pdev, table->msix_arr, nvec);
> > - if (err <= 0) {
> > + if (err) {
> > + kfree(table->msix_arr);
> > return err;
> > - } else if (err > MLX5_EQ_VEC_COMP_BASE) {
> > - nvec = err;
> > - goto retry;
> > }
> >
>
> According to latest sources, pci_enable_msix() may still fail so why
> do you want to remove this code?

pci_enable_msix() may fail, but it can not return a positive number.

We first calculate how many MSI-Xs we need, adjust to what we can get,
check if that is enough and only then go for it.

> > - mlx5_core_dbg(dev, "received %d MSI vectors out of %d requested\n", err, nvec);
> > - kfree(table->msix_arr);
> > + table->num_comp_vectors = nvec - MLX5_EQ_VEC_COMP_BASE;
> >
> > - return -ENOSPC;
> > + return 0;
> > }
> >
> > static void mlx5_disable_msix(struct mlx5_core_dev *dev)

--
Regards,
Alexander Gordeev
agordeev@redhat.com